import java.util.Scanner;

public class No289 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();

        int sum = 0;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);

            if (Character.isDigit(c)) {
                sum += Character.digit(c, 10);
            }
        }

        System.out.println(sum);

        sc.close();
    }

}